A standard disk for calibrating head-disk interference measuring equipment

A technique is described for producing standard disks for calibrating head-disk interference measuring equipment. The technique is more accurate than conventional methods, and yields disks with a much longer useful life. The method used is to sputter a group of small pads of tungsten onto a conventional oxide-coated rigid disk. The pads have a range of heights similar to the anticipated flying height of the head-disk combination under consideration. A glide-test head is then flown over the pads, and accurate thresholds are set according to the head output signal. It is shown how the thresholds can easily be set to an accuracy of ±1μ.